The most-challenging airports are those with safety hazards. These hazards may be topographical, weather-related, traffic-related or caused by congestion on the ground. Operational changes also create hazards.
There are a number of airports with ground contours on or near the airport that create problems. Some examples:
- San Diego, CA’s Lindbergh was notorious for planes having to maintain considerable altitude to avoid the Hillcrest neighborhood, and then having to descend precipitously in order to get the wheels onto the runway with enough length ahead in order to stop safely.
- Gustav III Airport on the Caribbean island of St. Barthelemy has a runway that runs from the foot of a hill to the beach, offering disaster to any pilot who might land short or long, heading in either direction.
- At Lukla, Nepal, Tenzing-Hillary Airport, the west end of the runway points directly at nearby high ground, while the east end of the runway starts on the edge of a 600-meter cliff.
Weather issues are a normal part of a pilot’s workday, unless they change significantly or violently during the final approach to a landing. Besides the airports that close frequently for strong crosswinds, swirling wind patterns and intermittent winds.
Denver, CO’s International airport has to close parts or all of the airport at times because strong crosswinds can push an aircraft off the runway or taxiway and into ravines. Snow and ice can interfere with runway braking and steering.
Congested airspace and high traffic-volume causes aircraft to come into conflict over the same airspace, compounding the errors by or difficulties facing air traffic controllers, leading to close calls and near-miss incidents, threatening aerial collisions. And FAA is under constant pressure from airports and airlines to reduce the required lateral separation and following intervals between planes, to increase the number of flights that can be handled.
Airline hub operations, heavy traffic, local weather conditions and diverted traffic because of weather elsewhere can clog airport facilities and pavement spaces, threatening collisions on the runways and other areas. The worst accident at such an airport involved two Boeing 747s at Tenerife, in the Azores on March 27, 1977, when fog and crowding had one plane crossing an active runway while another was taking off, killing 583 persons.
Equipment malfunctions and airport construction/maintenance also lead to dangerous situations. Navigation and landing aids are built to very demanding requirements for reliability, but occasional malfunctions or maintenance can take those systems out of service. All airports must build, maintain and occasionally change airport facilities, leading to runway and taxiway hazards or closures. The operational changes required to compensate for these issues can create uncertainty, confusion and dangerous situations.